GLOSSARY - Bioaugmentation for Groundwater Remediation - page 369

Methanogen (methanogenic bacteria) ‐ A microorganism that exists in anaerobic
environments and produces methane as the end product of its metabolism. Methanogens use
carbon dioxide, or simple carbon compounds such as methanol, as an electron acceptor.

Methanogenesis Process of producing methane gas during biological metabolism. ‐

Methanotroph (methanotrophic bacteria) ‐ A microorganism able to metabolize methane as
its only source of carbon and energy. Methanotrophs can grow aerobically or anaerobically and
require single-carbon compounds to survive.

Methyl tertiary butyl ether (MTBE) ‐ Also known as methyl tert -butyl ether. MTBE is
added to gasoline as an octane enhancer, originally developed to replace tetraethyl lead. It
rapidly became a widespread groundwater contaminant because of its high solubility and
recalcitrance to biodegradation.

Micelle ‐ An aggregate of surfactant molecules dispersed in a liquid colloid. A typical micelle
in aqueous solution forms an aggregate with the hydrophilic “head” regions in contact with
surrounding solvent, sequestering the hydrophobic single-tail regions in the micelle center.

Microautoradiography ‐ An autoradiograph is an image produced by the radiation emitted
from a specimen, such as a section of tissue, that has been treated with or has absorbed a
radiolabeled isotope. In biology, this technique is often used to determine the location of a
radioactive substance that has been introduced into a metabolic pathway or bound to a receptor
or macromolecule. Microautoradiography refers to the application of these techniques to
localize substances at the cellular level.

Microcosm ‐ A laboratory vessel set up to resemble as closely as possible the conditions of a
natural environment.

Mineralization ‐ The complete degradation of an organic chemical or organism to carbon
dioxide, water, and possibly other inorganic compounds or elements.

Molecular biological tool (MBT) ‐ Laboratory test that can measure the presence and/or
activity of microbes at a site. MBTs can be used to assess the potential for and performance of
monitored natural attenuation and bioremediation strategies for remediation of environmental
contaminants.

Monitored natural attenuation (MNA) ‐ Refers to the reliance on natural attenuation
processes (within the context of a carefully controlled and monitored site cleanup approach)
to achieve site-specific remediation objectives within a timeframe that is reasonable compared
to that offered by other more active methods.

Monod kinetics ‐ Equation based on the Michaelis-Menten equation for enzyme kinetics that
relates a bacterial culture's specific growth rate ( m ) to the substrate concentration (s). Requires
empirically derived parameters for the maximum growth rate ( m max ) with excess substrate
available, and the half-maximal saturation constant (K s ), the substrate concentration at which
the growth rate is half of m max . The fundamental equation is

S

m ¼ m max

K s +S :